Hobie 18's have a roler furling jib, you just release the jib sheets and pull on the furling line that leads from the furling drum and runs back to the tramp under the front cross-bar. Are you missing the furling line? Is your drum empty, or maybe missing?

Paul, look in the for sale section to see a picture of a furler for sale, it should look just like that. The string coming out of the bottom is what you pull on to wind up the jib. If you don't have one, there you go!